TFIIB-related factor 2 is associated with poor prognosis of nonsmall cell lung cancer patients through promoting tumor epithelial-mesenchymal transition

MAF1 is a predictive biomarker in HER2 positive breast cancer

RNA polymerase III transcription is pivotal in regulating cellular growth and frequently deregulated in various cancers. MAF1 negatively regulates RNA polymerase III transcription. Currently, it is unclear if MAF1 is universally deregulated in human cancers. Recently, MAF1 expression has been demonstrated to be altered in colorectal and liver carcinomas and Luminal B breast cancers. In this study, we analyzed clinical breast cancer datasets to determine if MAF1 alterations correlate with clinical outcomes in HER2-positive breast cancer. Using various bioinformatics tools, we screened breast cancer datasets for alterations in MAF1 expression. We report that MAF1 is amplified in 39% of all breast cancer sub-types, and the observed amplification co-occurs with MYC. MAF1 amplification correlated with increased methylation of the MAF1 promoter and MAF1 protein expression is significantly decreased in luminal, HER2-positive, and TNBC breast cancer subtypes. MAF1 protein expression is also significantly reduced in stage 2 and 3 breast cancer compared to normal and significantly decreased in all breast cancer patients, regardless of race and age. In SKBR3 and BT474 breast cancer cell lines treated with anti-HER2 therapies, MAF1 mRNA expression is significantly increased. In HER2-positive breast cancer patients, MAF1 expression significantly increases and correlates with five years of relapse-free survival in response to trastuzumab treatment, suggesting MAF1 is a predictive biomarker in breast cancer. These data suggest a role for MAF1 alterations in HER2-positive breast cancer. More extensive studies are warranted to determine if MAF1 serves as a predictive and prognostic biomarker in breast cancer.

BDP1 as a biomarker in serous ovarian cancer

BACKGROUND

TFIIIB, an RNA polymerase III specific transcription factor has been found to be deregulated in human cancers with much of the research focused on the TBP, BRF1, and BRF2 subunits. To date, the TFIIIB specific subunit BDP1 has not been investigated in ovarian cancer but has previously been shown to be deregulated in neuroblastoma, breast cancer, and Non-Hodgkins lymphoma.

RESULTS

Using in silico analysis of clinically derived platforms, we report a decreased BDP1 expression as a result of deletion in serous ovarian cancer and a correlation with higher and advanced ovarian stages. Further analysis in the context of TP53 mutations, a major contributor to ovarian tumorigenesis, suggests that high BDP1 expression is unfavorable for overall survival and high BDP1 expression occurs in stages 2, 3 and 4 serous ovarian cancer. Additionally, high BDP1 expression is disadvantageous and unfavorable for progression-free survival. Lastly, BDP1 expression significantly decreased in patients treated with first-line chemotherapy, platin and taxane, at twelve-month relapse-free survival.

CONCLUSIONS

Taken together with a ROC analysis, the data suggest BDP1 could be of clinical relevance as a predictive biomarker in serous ovarian cancer. Lastly, this study further demonstrates that both the over- and under expression of BDP1 warrants further investigation and suggests BDP1 may exhibit dual function in the context of tumorigenesis.

BDP1 Alterations Correlate with Clinical Outcomes in Breast Cancer

Simple Summary

Breast cancer accounts for 30% of all new cancer diagnoses in the United States. The most common type of breast cancer is invasive breast cancer. A hallmark trait of breast cancer is uncontrolled cell growth due to genetic alterations. TFIIIB-mediated RNA polymerase III transcription is specifically deregulated in human cancers. The TFIIIB BDP1 subunit is not well characterized in human cancer. The objective of this study was to analyze publicly available clinical cancer datasets to determine if BDP1 alterations correlate with clinical outcomes in available breast cancer datasets. BDP1 copy number and expression negatively correlate with breast cancer outcomes, including stage, grade, and mortality.

Abstract

TFIIIB is deregulated in a variety of cancers. However, few studies investigate the TFIIIB subunit BDP1 in cancer. BDP1 has not been studied in breast cancer patients. Herein, we analyzed clinical breast cancer datasets to determine if BDP1 alterations correlate with clinical outcomes. BDP1 copy number (n = 1602; p = 8.03 × 10⁻⁹) and mRNA expression (n = 130; p = 0.002) are specifically decreased in patients with invasive ductal carcinoma (IDC). In IDC, BDP1 copy number negatively correlates with high grade (n = 1992; p = 2.62 × 10⁻¹⁹) and advanced stage (n = 1992; p = 0.005). BDP1 mRNA expression also negatively correlated with high grade (n = 55; p = 6.81 × 10⁻⁴) and advanced stage (n = 593; p = 4.66 × 10⁻⁴) IDC. Decreased BDP1 expression correlated with poor clinical outcomes (n = 295 samples): a metastatic event at three years (p = 7.79 × 10⁻⁷) and cancer reoccurrence at three years (p = 4.81 × 10⁻⁷) in IDC. Decreased BDP1 mRNA correlates with patient death at three (p = 9.90 × 10⁻⁶) and five (p = 1.02 × 10⁻⁶) years. Both BDP1 copy number (n = 3785; p = 1.0 × 10⁻¹⁴) and mRNA expression (n = 2434; p = 5.23 × 10⁻⁶) are altered in triple-negative invasive breast cancer (TNBC). Together, these data suggest a role for BDP1 as potential biomarker in breast cancer and additional studies are warranted.

Targeting BRF2 in Cancer Using Repurposed Drugs

Simple Summary

BRF2, a subunit of the RNA polymerase III transcription complex, is upregulated in a wide variety of cancers and is a potential therapeutic target; however, no effective drugs are available to target BRF2. The upregulation of BRF2 in cancer cells confers survival via the prevention of oxidative stress-induced apoptosis. In this manuscript, we report the identification of potential BRF2 inhibitors through in silico drug repurposing screening. We further characterized bexarotene as a hit compound for the development of selective BRF2 inhibitors and provide experimental validation to support the repurposing of this FDA-approved drug as an agent to reduce the cellular levels of ROS and consequent BRF2 expression in cancers with elevated levels of oxidative stress.

Abstract

The overexpression of BRF2, a selective subunit of RNA polymerase III, has been shown to be crucial in the development of several types of cancers, including breast cancer and lung squamous cell carcinoma. Predominantly, BRF2 acts as a central redox-sensing transcription factor (TF) and is involved in rescuing oxidative stress (OS)-induced apoptosis. Here, we showed a novel link between BRF2 and the DNA damage response. Due to the lack of BRF2-specific inhibitors, through virtual screening and molecular dynamics simulation, we identified potential drug candidates that interfere with BRF2-TATA-binding Protein (TBP)-DNA complex interactions based on binding energy, intermolecular, and torsional energy parameters. We experimentally tested bexarotene as a potential BRF2 inhibitor. We found that bexarotene (Bex) treatment resulted in a dramatic decline in oxidative stress and Tert-butylhydroquinone (tBHQ)-induced levels of BRF2 and consequently led to a decrease in the cellular proliferation of cancer cells which may in part be due to the drug pretreatment-induced reduction of ROS generated by the oxidizing agent. Our data thus provide the first experimental evidence that BRF2 is a novel player in the DNA damage response pathway and that bexarotene can be used as a potential inhibitor to treat cancers with the specific elevation of oxidative stress.

P3H4 Overexpression Serves as a Prognostic Factor in Lung Adenocarcinoma

Background

The present study is aimed at evaluating the functional and clinical values of P3H4 in lung adenocarcinoma. Moreover, we also investigated the downstream pathways that P3H4 might participate in.

Methods

The differential expression analysis was used to identify genes differentially expressed in lung adenocarcinoma tissues as compared with normal tissues. Survival analysis was used to test the association between P3H4 and survival time. Gene set enrichment analysis was conducted to explore the downstream pathways. CCK8 and transwell were employed to examine the impact of P3H4 on cell phenotypes.

Results

P3H4 was highly upregulated in LUAD tissues at both RNA and protein levels. Moreover, the LUAD patients, who had high expression of P3H4, were also observed to have shorter disease-free survival and overall survival. These results demonstrated that P3H4 could be used as a prognostic biomarker for LUAD. Moreover, we also found that it was the copy number alterations (CNAs), not DNA methylation, that regulated the RNA expression of P3H4, indicating that its upregulation might be partially resulted from the CNAs. Furthermore, functional experiments revealed that the A549 and H1299 cells with siRNA treatment (siP3H4) exhibited significantly decreased cell proliferation after 24 hours, migratory ability, and invasiveness. Functionally, the upregulated proteins in the P3H4 high expression group were mainly enriched in tumor microenvironment-related pathways such as phagosome, focal adhesion, and ECM-receptor interaction and cancer-related pathways such as bladder cancer pathway, proteoglycans in cancer, and hippo signaling pathway.

Conclusion

The present study systematically evaluated the functional and clinical values of P3H4 in LUAD, and explored the related biological pathways. P3H4 might promote LUAD progression through regulating tumor microenvironment-related pathways.

TFIIB-related factor 2 regulates glucose-regulated protein 78 expression in acquired middle ear cholesteatoma

Acquired middle ear cholesteatoma leads to hearing loss, ear discharge, ear pain, and more serious intracranial complications. However, there is still no effective treatment other than surgery. TFIIB-related factor 2 (BRF2) acted as a redox sensor overexpressing in oxidative stress which linked endoplasmic reticulum (ER) stress, while glucose-regulated protein 78 (GRP78) was a biomarker of ER stress in cancer, atherosclerosis and inflammation. In our study, we investigated the roles of BRF2 and GRP78 in acquired middle ear cholesteatoma. Our results revealed that the expression of BRF2 was significant increased in acquired middle ear cholesteatoma, and which was positively correlated with the expression of GRP78. In addition, BRF2 and GRP78 showed colocalization in epithelium of acquired middle ear cholesteatomas and HaCaT cells. Prolongation of LPS stimulation in HaCaT cells escalated the expression of BRF2 and GRP78. To confirm the role of BRF2 and GRP78, we transfected si-BRF2 into HaCaT cells. All results indicated that BRF2 expression positively regulates the expression of GRP78 and may participate in the pathogenesis of acquire middle ear cholesteatoma.

A meta-analysis of BRF2 as a prognostic biomarker in invasive breast carcinoma

BACKGROUND

Deregulation of the RNA polymerase III specific TFIIIB subunit BRF2 occurs in subtypes of human cancers. However, correlations between BRF2 alterations and clinical outcomes in breast cancer are limited. We conducted this review to analyze BRF2 alterations in genomic data sets housed in Oncomine and cBioPortal to identify potential correlations between BRF2 alterations and clinical outcomes.

METHODS

The authors queried both Oncomine and cBioPortal for alterations in BRF2 in human cancers and performed meta-analyses identifying significant correlations between BRF2 and clinical outcomes in invasive breast cancer (IBC).

RESULTS

A meta cancer outlier profile analysis (COPA) of 715 data sets (86,733 samples) in Oncomine identified BRF2 as overexpressed in 60% of breast cancer data sets. COPA scores in IBC data sets (3594 patients) are comparable for HER2 (24.211, median gene rank 60) and BRF2 (29.656, median gene rank 36.5). Overall survival in IBC patients with BRF2 alterations (21%) is significantly decreased (p = 9.332e-3). IBC patients with BRF2 alterations aged 46 to 50 have a significantly poor survival outcome (p = 7.093e-3). Strikingly, in metastatic breast cancer, BRF2 is altered in 33% of women aged 45-50. BRF2 deletions are predominant in this age group.

CONCLUSION

This study suggests BRF2 may be an prognostic biomarker in invasive breast carcinoma.

RNA polymerase III transcription as a disease factor

In this review, Yeganeh et al. summarize different human diseases that have been linked to defects in the Pol III transcription apparatus or to Pol III products imbalance and discuss the possible underlying mechanisms.

RNA polymerase (Pol) III is responsible for transcription of different noncoding genes in eukaryotic cells, whose RNA products have well-defined functions in translation and other biological processes for some, and functions that remain to be defined for others. For all of them, however, new functions are being described. For example, Pol III products have been reported to regulate certain proteins such as protein kinase R (PKR) by direct association, to constitute the source of very short RNAs with regulatory roles in gene expression, or to control microRNA levels by sequestration. Consistent with these many functions, deregulation of Pol III transcribed genes is associated with a large variety of human disorders. Here we review different human diseases that have been linked to defects in the Pol III transcription apparatus or to Pol III products imbalance and discuss the possible underlying mechanisms.

MicroRNA-425-5p Inhibits Lung Cancer Cell Growth in Vitro and in Vivo by Downregulating TFIIB-Related Factor 2

Lung cancer is the most common cancer type with increasingly high incidence. MicroRNAs provide the potential biomarkers for lung cancer treatment. Thus, we aimed to investigate the function of microRNA-425-5p in lung cancer development and the underlying mechanisms. MicroRNA-425-5p overexpression inhibited A549 lung cancer cell proliferation in vitro and in vivo. On the other hand, microRNA-425-5p inhibition increased A549 proliferation. Mechanistically, the underlying mechanism by which microRNA-425-5p inhibits lung cancer cell growth was mediated through its ability in targeting and downregulating the TFIIB-related factor 2. Our results for the first time identified microRNA-425-5p as a tumor suppressor in lung cancer. Thus, microRNA-425-5p may serve as a potential therapeutic target for lung cancer.

Silencing of BRF2 inhibits the growth and metastasis of lung cancer cells

Transcription factor II B (TFIIB)‑related factor 2 (BRF2) is involved in the development of cancer, but its role in lung cancer is underreported. The present study aimed to explore the role of BRF2 in the regulation of lung cancer cells. Immunofluorescence staining and immunohistochemistry were performed to detect BRF2 protein expression in human lung cancer cells and tissues. Following cell transfection with small interfering RNA for silencing BRF2, the cell proliferation was examined by Cell Counting Kit‑8 and MTT assays. Cell apoptosis, migration and invasion were determined by flow cytometry, wound‑healing and Transwell assay. The expression levels of Akt, phosphorylated (p)‑Akt, Bax, E‑cadherin, Bcl‑2, N‑cadherin, Snail and epidermal growth factor receptor (EGFR) in human lung cancer A549 cells were detected by western blotting. The results demonstrated that BRF2 expression was increased in human lung cancer cells and tissues, and that silencing of BRF2 promoted cell apoptosis but inhibited cell proliferation and migration. The protein expression levels of Akt, E‑cadherin, p‑Akt, Bcl‑2, N‑cadherin, Snail and EGFR in A549 cells were inhibited by silencing of BRF2, while expression levels of Bax and E‑cadherin were increased by silencing BRF2. In conclusion, BRF2 demonstrates high expression in lung cancer and silencing of BRF2 inhibits the growth and metastasis of lung cancer cells. The current findings provide a novel approach for the treatment of lung cancer.

BRF2 as a promising indicator for radical lymph-node dissection surgery in patients with cN0 squamous cell carcinoma of the middle thoracic esophagus

PURPOSE

Radical lymph-node dissection surgery in patients with cN0 middle thoracic esophageal squamous cell carcinoma (ESCC) remains controversial. We sought a novel biomarker that could be used for decision-making in relation to radical lymph-node dissection.

METHODS

One hundred and nineteen patients with cN0 middle thoracic ESCC undergoing three-field lymph-node dissection (3FLND) or two-field lymph-node dissection (Ivor Lewis) esophagectomy were reviewed. A survival analysis, and Chi-square and parametric tests were performed.

RESULTS

A Cox regression analysis revealed that the expression of BRF2 was an independent prognostic factor for overall survival (P = 0.014) and progression-free survival (P = 0.014). The survival of patients who underwent 3FLND was better than that of patients who underwent Ivor Lewis esophagectomy in the BRF2 overexpression group (P = 0.002), but not in the BRF2 nonoverexpression group (P = 0.386). The risk of lymph-node recurrence and the number of recurrent lymph nodes in patients with the overexpression of BRF2 were increased in the Ivor Lewis group in comparison to the 3FLND group (P = 0.01 and P < 0.001). The risk of cervical and superior mediastinal lymph-node recurrence was positively correlated with the overexpression of BRF2 (P = 0.027). Furthermore, in the Ivor Lewis group, a significant correlation was found between the risk of lymph-node recurrence or the number of recurrent lymph nodes and the expression of BRF2 (P = 0.002 and P = 0.004), but not in the 3FLND group (P = 0.193 and P = 0.694).

CONCLUSIONS

3FLND generated better survival outcomes and reduced the rate of lymph-node recurrence in comparison to Ivor Lewis in patients with the overexpression of BRF2. BRF2 can be used as an indicator for radical lymph-node dissection surgery in cN0 ESCC patients.

MicroRNA-373 Inhibits Cell Proliferation and Invasion via Targeting BRF2 in Human Non-small Cell Lung Cancer A549 Cell Line

Purpose

The purpose of this study was to investigate the biological role and mechanism of miR-373 targeting of TFIIB-related factor 2 (BRF2) in the regulation of non-small cell lung cancer (NSCLC) cells.

Materials and Methods

miRNA microarray chip analysis of four paired NSCLC and adjacent non-tumor tissues was performed. Quantitative real-time polymerase chain reaction (qRT-PCR) andwestern blotting were used to detect the expression levels of miR-373 and BRF2 in NSCLC tissues and cell lines. The dual-luciferase reporter method was performed to determine if BRF2 is a target of miR-373. MTT, wound-healing, Transwell, and flow cytometric assays were conducted to examine the proliferation, migration, invasion, and cell cycle progression of NSCLC A549 cells, respectively; western blotting was used to detect the expression of epithelial-mesenchymal transition (EMT)–related proteins.

Results

The miRNA microarray chip analysis demonstrated that miR-373 was down-regulated in NSCLC tissues, and this result was confirmed by qRT-PCR. Additionally, miR-373 was confirmed to target BRF2. Moreover, miR-373 expression was inversely correlated with BRF2 expression in NSCLC tissues and cell lines; both miR-373 down-regulation and BRF2 up-regulation were strongly associated with the clinicopathological features and prognosis of NSCLC patients. In vitro, overexpression of miR-373 markedly inhibited cell proliferation, migration, and invasion; up-regulated the expression of E-cadherin; and down-regulated the expression of N-cadherin and Snail in A549 cell. Knockdown BRF2 by siRNA resulted in effects similar to those caused by overexpression of miR-373.

Conclusion

MiR-373 is decreased in NSCLC, and overexpression of miR-373 can suppress cell EMT, and inhibit the proliferation, migration, and invasion of NSCLC A549 cells by targeting BRF2.

Epigenetic regulation of noncoding RNA transcription by mammalian RNA polymerase III

RNA polymerase III (Pol III) synthesizes a range of medium-sized noncoding RNAs (collectively 'Pol III genes') whose early established biological roles were so essential that they were considered 'housekeeping genes'. Besides these fundamental functions, diverse unconventional roles of mammalian Pol III genes have recently been recognized and their expression must be exquisitely controlled. In this review, we summarize the epigenetic regulation of Pol III genes by chromatin structure, histone modification and CpG DNA methylation. We also recapitulate the association between dysregulation of Pol III genes and diseases such as cancer and neurological disorders. Additionally, we will discuss why in-depth molecular studies of Pol III genes have not been attempted and how nc886, a Pol III gene, may resolve this issue.

Discovery of novel plasma proteins as biomarkers for the development of incisional hernias after midline incision in patients with colorectal cancer: The ColoCare study

BACKGROUND

Ventral incisional hernia is the most common long-term complication after an abdominal operation. Among newly diagnosed colorectal cancer patients, we screened the preoperative plasma proteome to explore predictive markers for the development of an incisional hernia.

METHODS

We utilized preoperative plasma samples of 72 newly diagnosed colorectal cancer patients who underwent midline incision for tumor resection between 2010 and 2013. A total of 21 patients with incisional hernia occurrence were matched with 51 patients with at least 18 months follow-up without an incisional hernia by sex, age, and body mass index. To assess predictive markers of incisional hernia risk, we screened the plasma proteome for >2,000 distinct proteins using a well-validated antibody microarray test. Paired t tests were used to compare protein levels between cases and controls. A gene-set-enrichment analysis (Gene Ontology and Kyoto Encyclopedia of Genes and Genomes) was applied to test for differences in signaling pathways between the 2 groups.

RESULTS

The proteome screen identified 25 proteins that showed elevated or reduced plasma levels in the hernia group compared to the control group (nominal P values < .05). Several proteins were in pathways associated with wound healing (CCL21, SHBG, BRF2) or cell adhesion (PCDH15, CDH3, EPCAM).

CONCLUSION

Our study shows that there are multiple individual and groups of plasma proteins that could feasibly predict the personal hernia risk prior to undergoing an operation. Further investigations in larger, independent sample sets are warranted to replicate findings and validate clinical utility of potential biomarkers. After validation, such a biomarker could be incorporated into a multifactorial risk model to guide clinical decision-making.

Identification of 42 Genes Linked to Stage II Colorectal Cancer Metastatic Relapse

Colorectal cancer (CRC) is one of the leading causes of cancer mortality. Metastasis remains the primary cause of CRC death. Predicting the possibility of metastatic relapse in early-stage CRC is of paramount importance to target therapy for patients who really need it and spare those with low-potential of metastasis. Ninety-six stage II CRC cases were stratified using high-resolution array comparative genomic hybridization (aCGH) data based on a predictive survival algorithm and supervised clustering. All genes included within the resultant copy number aberrations were each interrogated independently at mRNA level using CRC expression datasets available from public repositories, which included 1820 colon cancers, and 167 normal colon tissues. Reduced mRNA expression driven by copy number losses and increased expression driven by copy number gains revealed 42 altered transcripts (29 reduced and 13 increased transcripts) associated with metastatic relapse, short disease-free or overall survival, and/or epithelial to mesenchymal transition (EMT). Resultant genes were classified based on gene ontology (GO), which identified four functional enrichment groups involved in growth regulation, genomic integrity, metabolism, and signal transduction pathways. The identified 42 genes may be useful for predicting metastatic relapse in stage II CRC. Further studies are necessary to validate these findings.

RNA Polymerase III Advances: Structural and tRNA Functional Views

RNA synthesis in eukaryotes is divided among three RNA polymerases (RNAPs). RNAP III transcribes hundreds of tRNA genes and fewer additional short RNA genes. We survey recent work on transcription by RNAP III including an atomic structure, mechanisms of action, interactions with chromatin and retroposons, and a conserved link between its activity and a tRNA modification that enhances mRNA decoding. Other new work suggests important mechanistic connections to oxidative stress, autoimmunity and cancer, embryonic stem cell pluripotency, and tissue-specific developmental effects. We consider that, for some of its complex functions, variation in RNAP III activity levels lead to nonuniform changes in tRNAs that can shift the translation profiles of key codon-biased mRNAs with resultant phenotypes or disease states.

Induction of proto-oncogene BRF2 in breast cancer cells by the dietary soybean isoflavone daidzein

BACKGROUND

BRF2 is a transcription factor required for synthesis of a small group of non-coding RNAs by RNA polymerase III. Overexpression of BRF2 can transform human mammary epithelial cells. In both breast and lung cancers, the BRF2 gene is amplified and overexpressed and may serve as an oncogenic driver. Furthermore, elevated BRF2 can be independently prognostic of unfavorable survival. Dietary soy isoflavones increase metastasis to lungs in a model of breast cancer and a recent study reported significantly increased cell proliferation in breast cancer patients who used soy supplementation. The soy isoflavone daidzein is a major food-derived phytoestrogen that is structurally similar to estrogen. The putative estrogenic effect of soy raises concern that high consumption of soy foods by breast cancer patients may increase tumor growth.

METHODS

Expression of BRF2 RNA and protein was assayed in ER-positive or -negative human breast cancer cells after exposure to daidzein. We also measured mRNA stability, promoter methylation and response to the demethylating agent 5-azacytidine. In addition, expression was compared between mice fed diets enriched or deprived of isoflavones.

RESULTS

We demonstrate that the soy isoflavone daidzein specifically stimulates expression of BRF2 in ER-positive breast cancer cells, as well as the related factor BRF1. Induction is accompanied by increased levels of non-coding RNAs that are regulated by BRF2 and BRF1. Daidzein treatment stabilizes BRF2 and BRF1 mRNAs and selectively decreases methylation of the BRF2 promoter. Functional significance of demethylation is supported by induction of BRF2 by the methyltransferase inhibitor 5-azacytidine. None of these effects are observed in an ER-negative breast cancer line, when tested in parallel with ER-positive breast cancer cells. In vivo relevance is suggested by the significantly elevated levels of BRF2 mRNA detected in female mice fed a high-isoflavone commercial diet. In striking contrast, BRF2 and BRF1 mRNA levels are suppressed in matched male mice fed the same isoflavone-enriched diet.

CONCLUSIONS

The BRF2 gene that is implicated in cancer can be induced in human breast cancer cells by the isoflavone daidzein, through promoter demethylation and/or mRNA stabilization. Dietary isoflavones may also induce BRF2 in female mice, whereas the converse occurs in males.